// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/inspector/v8-regex.h"

#include <limits.h>

#include "src/inspector/string-util.h"
#include "src/inspector/v8-inspector-impl.h"

#include "include/v8-inspector.h"

namespace v8_inspector {

V8Regex::V8Regex(V8InspectorImpl* inspector, const String16& pattern,
    bool caseSensitive, bool multiline)
    : m_inspector(inspector)
{
    v8::Isolate* isolate = m_inspector->isolate();
    v8::HandleScope handleScope(isolate);
    v8::Local<v8::Context> context = m_inspector->regexContext();
    v8::Context::Scope contextScope(context);
    v8::TryCatch tryCatch(isolate);

    unsigned flags = v8::RegExp::kNone;
    if (!caseSensitive)
        flags |= v8::RegExp::kIgnoreCase;
    if (multiline)
        flags |= v8::RegExp::kMultiline;

    v8::Local<v8::RegExp> regex;
    if (v8::RegExp::New(context, toV8String(isolate, pattern),
            static_cast<v8::RegExp::Flags>(flags))
            .ToLocal(&regex))
        m_regex.Reset(isolate, regex);
    else if (tryCatch.HasCaught())
        m_errorMessage = toProtocolString(isolate, tryCatch.Message()->Get());
    else
        m_errorMessage = "Internal error";
}

int V8Regex::match(const String16& string, int startFrom,
    int* matchLength) const
{
    if (matchLength)
        *matchLength = 0;

    if (m_regex.IsEmpty() || string.isEmpty())
        return -1;

    // v8 strings are limited to int.
    if (string.length() > INT_MAX)
        return -1;

    v8::Isolate* isolate = m_inspector->isolate();
    v8::HandleScope handleScope(isolate);
    v8::Local<v8::Context> context = m_inspector->regexContext();
    v8::Context::Scope contextScope(context);
    v8::MicrotasksScope microtasks(isolate,
        v8::MicrotasksScope::kDoNotRunMicrotasks);
    v8::TryCatch tryCatch(isolate);

    v8::Local<v8::RegExp> regex = m_regex.Get(isolate);
    v8::Local<v8::Value> exec;
    if (!regex->Get(context, toV8StringInternalized(isolate, "exec"))
             .ToLocal(&exec))
        return -1;
    v8::Local<v8::Value> argv[] = {
        toV8String(isolate, string.substring(startFrom))
    };
    v8::Local<v8::Value> returnValue;
    if (!exec.As<v8::Function>()
             ->Call(context, regex, arraysize(argv), argv)
             .ToLocal(&returnValue))
        return -1;

    // RegExp#exec returns null if there's no match, otherwise it returns an
    // Array of strings with the first being the whole match string and others
    // being subgroups. The Array also has some random properties tacked on like
    // "index" which is the offset of the match.
    //
    // https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/RegExp/exec

    DCHECK(!returnValue.IsEmpty());
    if (!returnValue->IsArray())
        return -1;

    v8::Local<v8::Array> result = returnValue.As<v8::Array>();
    v8::Local<v8::Value> matchOffset;
    if (!result->Get(context, toV8StringInternalized(isolate, "index"))
             .ToLocal(&matchOffset))
        return -1;
    if (matchLength) {
        v8::Local<v8::Value> match;
        if (!result->Get(context, 0).ToLocal(&match))
            return -1;
        *matchLength = match.As<v8::String>()->Length();
    }

    return matchOffset.As<v8::Int32>()->Value() + startFrom;
}

} // namespace v8_inspector
